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Heh. It could be telling that I had to look up the expansion for TLB. CPU cache implementation... holy crap.

My ex-coworker has done the vanilla scope thing too and has a 400MHz scope at home. For some reason people like this are not too uncommon in Finnish oldskool[tm] IT scene. I remember how he isolated a latency and concurrency bug to an expensive interrupt handler. Rewriting isolated parts of core kernel code to make a really tricky problem go away was one of his more hardcore skills.

I'm not even near his level. My own experience is limited to slightly nibbling the edges of file system and block cache behaviour. It's a brave person who dares dive into that code. Not me.

But I do know one person who regularly works with decapped chips. He works for a company who do extremely low-level hardware investigations. Now that's hardcore.

Cache bugs are one of the fun ones. You think you're losing your mind and the people around you would probably agree. A couple of weeks go by, your spouse is ready to fire you, your boss wants to divorce you, and every waking moment is full of race conditions. Four-way stops on the drive to work are a source of stress and you punch buttons in the elevator and worry about firmware bugs. Then you get to your desk and there's the setup, a laughably small board for all the trouble it's made, and it's time for single combat, Sherlock Holmes style.

When you find the problem it's usually a blinding flash of realization that illuminates a tiny, eensy bit of code that you tweak and make right in a couple of minutes. Invariably the mistake was pretty stupid. The glory moment is over quickly because you know all the test cases will pass and that you've just nailed another one.

You've got bragging rights during one lunch, but that's it. It's off to more mundane bugs in the mortal world, and you feel a little sad.

I need to do hardware again.

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